We reduced the cost of building Mastodon at Twitter-scale by 100x

Post by cutler » Tue, Aug 15, 2023, 7:40 PM UTC

nathanmarz wrote: post #115

clusterhacks wrote: post #108

I'm excited to see the docs for Rama. But I am also a little scared of the comment " I came to suspect a new programming paradigm was needed" from Nathan. It's not so much that I think the comment is wrong or anything, but rather that it seems so similar to what I have heard in the past from power-lisp (or Clojure in this case) super-smart engineers. I feel like we have reached a point in software development where "…

This is why we exposed Rama as a Java API rather than Clojure or our internal language (which is defined with Clojure macros, so it's technically also Clojure). Rama's Java dataflow API is effectively a subset of our internal language, with operations like "partitioners" being implemented using continuations.

Post by kulahan » Tue, Aug 15, 2023, 7:41 PM UTC

jedberg wrote: post #55

Pxtl wrote: post #25

I've seen many people describe frameworks like this - you know, first you have the slow back-end event-driven master database that you don't query live against, then you've got eventual-consistency flows against the various data-warehouses and data-stores and partitioned sharded databases in useful query-friendly layouts that you actually read live from... and I never see it clearly explained: how do you read a chang…

The short answer is write-through cache. You write the update directly to the cache closest to the user and into the eventually consistent queue. We did this at reddit. When you make a comment the HTML is rendered and put straight into the cache, and the raw text is put into the queue to go into the database. Same with votes. I suspect they do this client side now, which is now the closest cache to the user, but back…

Post by sitzkrieg » Tue, Aug 15, 2023, 7:47 PM UTC

ceejayoz wrote: post #73

hot_gril wrote: post #57

Earlier quoted context omitted.

This is usually what I do. Don't even want to wait for an HTTP roundtrip for some of these, e.g. "liking" a post should fill in the heart icon or whatever instantly. One famous example of this going to far: Mac Mail app used to play a whoosh sound when your email is actually sent. They changed it to whoosh instantly no matter what. Given how often an email might fail to send or get delayed, this meant an actually use…

> Don't even want to wait for an HTTP roundtrip for some of these, e.g. "liking" a post should fill in the heart icon or whatever instantly. HN does this, and on slow days, about half of my upvotes don't go through.

Post by sitzkrieg » Tue, Aug 15, 2023, 7:49 PM UTC

nathanmarz wrote: post #13

sharms wrote: post #6

The performance on the example Mastodon instance is very responsive - almost anywhere I clicked loaded nearly instantly. I created an account and the only thing I found missing was it doesn't implement full text search unless my user was tagged, but that might be a Mastodon specific item. I think they have thought a lot about typical hard problems, such as having the timeline processing happen along side the pipeline…

That is indeed an intentional part of Mastodon's design, which we tried to be faithful to as much as possible. We originally implemented search across all statuses and had to reimplement it when we realized Mastodon is a little different.

Post by nathanmarz » Tue, Aug 15, 2023, 7:53 PM UTC

fiddlerwoaroof wrote: post #134

nathanmarz wrote: post #124

Earlier quoted context omitted.

The customer API in Java, and the implementation of that API is in Clojure.

Will there be a first-party Clojure wrapper? Or, would the expectation be that users would use Java interop?